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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   https://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  
20  package org.apache.bcel.classfile;
21  
22  import java.io.DataInput;
23  import java.io.DataOutputStream;
24  import java.io.IOException;
25  
26  import org.apache.bcel.Const;
27  
28  /**
29   * This class represents an entry in the provides table of the Module attribute. Each entry describes a service
30   * implementation that the parent module provides.
31   *
32   * @see Module
33   * @since 6.4.0
34   */
35  public final class ModuleProvides implements Cloneable, Node {
36  
37      private static String getImplementationClassNameAtIndex(final ConstantPool constantPool, final int index, final boolean compactClassName) {
38          final String className = constantPool.getConstantString(index, Const.CONSTANT_Class);
39          if (compactClassName) {
40              return Utility.compactClassName(className, false);
41          }
42          return className;
43      }
44      private final int providesIndex; // points to CONSTANT_Class_info
45      private final int providesWithCount;
46  
47      private final int[] providesWithIndex; // points to CONSTANT_Class_info
48  
49      /**
50       * Constructs object from file stream.
51       *
52       * @param file Input stream
53       * @throws IOException if an I/O Exception occurs in readUnsignedShort
54       */
55      ModuleProvides(final DataInput file) throws IOException {
56          providesIndex = file.readUnsignedShort();
57          providesWithCount = file.readUnsignedShort();
58          providesWithIndex = new int[providesWithCount];
59          for (int i = 0; i < providesWithCount; i++) {
60              providesWithIndex[i] = file.readUnsignedShort();
61          }
62      }
63  
64      /**
65       * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
66       * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
67       *
68       * @param v Visitor object
69       */
70      @Override
71      public void accept(final Visitor v) {
72          v.visitModuleProvides(this);
73      }
74  
75      /**
76       * @return deep copy of this object
77       */
78      public ModuleProvides copy() {
79          try {
80              return (ModuleProvides) clone();
81          } catch (final CloneNotSupportedException e) {
82              // TODO should this throw?
83          }
84          return null;
85      }
86  
87      /**
88       * Dump table entry to file stream in binary format.
89       *
90       * @param file Output file stream
91       * @throws IOException if an I/O Exception occurs in writeShort
92       */
93      public void dump(final DataOutputStream file) throws IOException {
94          file.writeShort(providesIndex);
95          file.writeShort(providesWithCount);
96          for (final int entry : providesWithIndex) {
97              file.writeShort(entry);
98          }
99      }
100 
101     /**
102      * Gets the array of implementation class names for this ModuleProvides.
103      * @param constantPool Array of constants usually obtained from the ClassFile object
104      * @param compactClassName false for original constant pool value, true to replace '/' with '.'
105      * @return array of implementation class names
106      * @since 6.10.0
107      */
108     public String[] getImplementationClassNames(final ConstantPool constantPool, final boolean compactClassName) {
109         final String[] implementationClassNames = new String[providesWithCount];
110         for (int i = 0; i < providesWithCount; i++) {
111             implementationClassNames[i] = getImplementationClassNameAtIndex(constantPool, providesWithIndex[i], compactClassName);
112         }
113         return implementationClassNames;
114     }
115 
116     /**
117      * Gets the interface name for this ModuleProvides.
118      * @param constantPool Array of constants usually obtained from the ClassFile object
119      * @return interface name
120      * @since 6.10.0
121      */
122     public String getInterfaceName(final ConstantPool constantPool) {
123         return constantPool.constantToString(providesIndex, Const.CONSTANT_Class);
124     }
125 
126     /**
127      * @return String representation
128      */
129     @Override
130     public String toString() {
131         return "provides(" + providesIndex + ", " + providesWithCount + ", ...)";
132     }
133 
134     /**
135      * @return Resolved string representation
136      */
137     public String toString(final ConstantPool constantPool) {
138         final StringBuilder buf = new StringBuilder();
139         final String interfaceName = getInterfaceName(constantPool);
140         buf.append(interfaceName);
141         buf.append(", with(").append(providesWithCount).append("):\n");
142         for (final int index : providesWithIndex) {
143             final String className = getImplementationClassNameAtIndex(constantPool, index, true);
144             buf.append("      ").append(className).append("\n");
145         }
146         return buf.substring(0, buf.length() - 1); // remove the last newline
147     }
148 }